The invention relates to a plug connector of an aircraft power supply device for the on-board power supply of aircraft, comprising a housing, which is divided so that it can be separated into at least two sections in the longitudinal direction, of which a first section, constituting the front housing element, has cylindrical first contact elements which, on the receiving side of the plugs, are embodied to be socket- or sleeve-shaped, and can be releasably connected on the side facing away from the plug receptacle with cylindrical second contact elements, such as plug sleeves, which extend from the second section of the housing, which forms the rear element, in which the second contact elements are connected with strands of a cable and encapsulated after having been connected.
Multi-conductor cables with plug connectors are used for the on-board power supply of aircraft, which are seated in a plug receptacle device arranged on board, which contains contact pins. A supply voltage of preferably 220 V, or respectively 112 V/400 Hz, as well as a d.c. voltage (28 V) for acknowledgements, are transmitted via the cables and plug connectors.
The plug connectors of known on-board power supplies respectively have a housing with bores, in which electrically conducting, cylinder-shaped bodies are arranged, which are connected on the inside of the housing with multi-conductor cables, and on their free outer ends are designed as sockets for receiving contact pins. The ends of the supply cables inserted into the plug connectors can be firmly connected with the electrically conducting cylinder-shaped bodies, wherein after assembly the empty space is filled with a sealing compound. In spite of their sturdiness, the housings of the plug connectors are often damaged on their front ends, for example by falling, so that further use is no longer possible. It can also occur that the sockets themselves are damaged. In all these cases the supply cable is cut off closely behind the plug connector in order to then firmly connect the strands with the cylinder-shaped body, embodied with sockets in the front free end of a new plug connector. If such a respective supply cable extends, for example, from a manual control panel, the length of the supply cable provided is normally limited to one to two meters, for example, so that only a limited number of replacements of plugs is possible until further cutting becomes impossible. In this case a new unit must be made available.
In order to supply an aircraft, for example, via the plug connector, the latter is plugged into the plug receptacle with contact pins, which is provided at the aircraft. It should be assured here, that the contact pins are maximally inserted into the sockets in order to assure the required output and signal transmissions through the plug connector to the aircraft. The output transmission, for example, can already take place with little contact. However, spark gaps are often formed, which lead to scorching. Moreover, in case of a fall, the contact pins and/or the sockets can be damaged if the contact pins have been only slightly inserted into the sockets.
If, for example, an aircraft runs over such a plug connector, there is the danger that the rear housing element becomes damaged. The result of this is that the entire plug connector must be replaced, i.e. it must be severed from the supply cable.
Moreover, with the known plug connectors, a step extends between the front element and rear housing element (DE 36 07 753 A1, DE 86 06 435 U1) which, when the plug is run over, can result in the breaking of the housing.
A plug connector of the type mentioned at the outset can be found in EP 0 236 923 B1. In order to make possible a simple change, or respectively replacement of damaged parts in case of damage to the front housing element, or respectively the first contact elements extending therein, it is provided that the first contact elements are releasably arranged in the first housing section. In this way damaged contacts can be replaced in the shortest time and, in particular in case of use at an airport, the damage can be repaired on the spot without having to accept long idle periods.
A corresponding plug can furthermore have a pilot contact for checking whether or not the plug connector has been correctly arranged in a plug receptacle.
Also known is a plug connector with a number of contact sockets arranged in an insulated body and with contact elements designed as a switch, wherein the switch is actuated by a hollow-cylindrical insulated pin projecting from a counter-plug element. The contact elements respectively consist of a conducting pin extending into a hollow cylinder and surrounded by resilient contact fingers. The contact fingers, pre-stressed by a spring, rest against the pin, by means of which a circuit with an indicator device is closed (U.S. Pat. No. 3,912,889).
In connection with otherwise known plug connectors which, however, are not suitable for the on-board power supply of aircraft, the housing can be assembled from half shells, which cannot be cast, and are connected in sections in a kind of groove-and-tongue connection (DE 33 13 144 C2).
The present invention is based on the problem of further developing a plug connector of the type mentioned at the outset in such a way, that damage to the front housing element as well as the rear housing element cannot result in having to replace the plug connector as a whole. In this connection the option of refurbishing housing elements themselves should be provided in particular which, however should be assembled in this way, but wherein heavy loads of, for example 10 t and more, no longer result in damage. It should moreover be assured that the front housing element does not melt in case of extensive heating of the first contact elements, or that, if this should be the case, a complete exchange is not necessary.
In accordance with the invention, the problem is essentially solved in that the front housing element consists of an outer shell body and of an insert, which is releasably arranged therein and has hollow-cylindrical receivers for the first contact elements. In this case the contact elements extend at least partially spaced apart from the hollow-cylindrical receiver receiving the contact element.
By means of the respective construction it is assured that cooling to the required extent can take place in the area of the first contact elements, which assures that, even if too powerful a current flows through the first contact elements, i.e. when a strong contact resistance is built up, melting of the front housing element does not occur because of the heating connected with this. It has been provided here in particular that the insert is made of a plastic material which is temperature-resistant to at 230.degree. C. Granamid or Stanyl.RTM., for example, can be used as the material.
But if melting should nevertheless occur because of the development of too high heat, only the receiver is affected by this, so that it would have to be replaced, while the outer shell body can be further used.
In accordance with a further development of the invention, the hollow-cylindrical receivers themselves are connected, spaced apart from each other, by strips. The insert should also be supported on the shell body by protrusions extending from the insert, such as strips extending in the longitudinal direction of the insert. The necessary "ventilation" of the front housing element is provided by means of this.
In accordance with a preferred embodiment of the invention, the shell body has protrusions, such as longitudinal strips, extending away from the exterior, whose outer surfaces extend flush in respect to the exterior of the rear housing element. It is assured by this that no step is formed between the front and rear housing elements, so that therefore a breaking of the plug connector is prevented if it is run over.
At least one switch element can extend in a known manner from the rear housing element, but in accordance with the invention this is fastened to a support plate which can be fixed in place in grooves in the half shells of the rear housing element which make a transition into each other, wherein the plate with the connecting line leading to the switch element is encapsulated together with the strands of the cable. This results in the advantage that during the exchange of the rear housing element a fresh connection of the switch element with signal lines is not required. Appropriate switches are required, for example for actuating cable rollers, or respectively to connect signal lines, or respectively to disconnected them.
In accordance with an original proposal for a solution it is proposed that the rear housing element consists of two half shells with longitudinal edges, which rest on each other and extend in the longitudinal direction of the housing, that, with the rear housing element assembled, the longitudinal edges form a labyrinth seal, and that the rear housing element is closed at the end toward the front housing element by means of an insert, through which the second contact elements extend, and which itself is sealed at the inside of the housing against the rear housing element by means of a labyrinth seal.
In contrast to the known prior art, the rear housing element is composed of half shells, which rest on each other in the longitudinal direction of the housing and are connected with each other. Here, the longitudinal edges are designed in such a way that, with the half shells assembled, a labyrinth seal is provided. This results in the advantage that shearing of the longitudinal edges is prevented when the rear housing element is placed under a load. In this connection it has been shown that weights of 10 t or more can act on the housing without there being a danger of damage.
Moreover, the labyrinth seal has the advantage that sealing compound cannot escape out of the sides when the rear housing element is filled with it. Therefore the housing elements cannot stick together in the areas of the seams between the housing elements. This means in turn that in case one housing half shell is damaged, the latter can be removed from the other half shell without problems in order to be replaced by a new one. In accordance with a further development of the invention, the half shells should be identically embodied in this case.
It has been provided in particular, that one of the longitudinal edges of the half shell has a strip-like longitudinal protrusion, and the other longitudinal edge has a depression, such as a groove, corresponding to the course of the strip-like longitudinal edge. In this way the half shells are connected with each other in a kind of a groove-and-tongue connection when the rear housing elements are assembled.
In a supplemental way it is possible to insert a sealing element, such as a toroidal cord, into the depression, such as a groove, wherein it is additionally assured that in the course of filling the rear housing element with sealer, the sealing compound cannot escape through the labyrinth seal.
In accordance with the invention, the rear housing element is closed at the side of the housing front end by an insert, through which second contact elements protrude. Here, the insert is sealed on the inside of the housing by means of a labyrinth seal against the rear housing element, or respectively its half shells. It has been provided in particular that the plate-shaped insert has at least one circumferential strip-like protrusion extending in the direction toward the inner housing shell wall, to which a corresponding depression, such as a groove, in the inner housing walls is assigned. However, preferably the insert should have two strip-like protrusions extending parallel in respect to each other, and the inner housing walls should have correspondingly matched, or respectively arranged, depressions, such as grooves. It is possible in this case to arrange a sealing element, such as a toroidal cord, in at least one of the depressions, such as grooves. It is also not necessary that a corresponding strip-like protrusion of the plate-shaped insert engages each one of the grooves circulating in the assembled rear housing element. Instead, it is sufficient if an appropriate strip of the insert is inserted only into the groove extending in the front housing element.
Not only is an assembly aid for aligning the second contact elements on the first provided by the use of the insert, but sealing of the rear housing element when the sealing compound is applied takes place in addition. Moreover, the rear housing element is provided with great sturdiness in its front area.
In a further development of the invention, which should be stressed in particular, the inner wall surfaces of the half shell extend in the form of a cone toward each other in the direction of their respective longitudinal edges. Accordingly, each half shell encloses a hollow space in the shape of a truncated pyramid, which provides the advantage that the half shells can be removed without problems after the setting of the sealing compound and, if necessary, can be replaced by new ones.
In order to make a pouring aid for the sealing compound available, the rear housing end should have an opening widened in the shape of a trumpet, through which the cables also extend.